Zulip - Chat for distributed teams. Zulip combines the immediacy of real-time chat with an email threading model. With Zulip, you can catch up on important conversations while ignoring irrelevant ones.

Houseparty - Brining empathy to online communication.

Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.

Booyah - Video chat with up to 12 friends at the same time.

Twitch Messenger - Desktop and mobile app for Twitch users to communicate with friends and teammates across platforms.

Airtime - Hang out with group video, share music & videos